1. Field of the Invention
This invention relates to the production of three-dimensional images for television, motion pictures, video games and the like.
2. Description of the Prior Art
Various techniques have been used in the past to produce stereoscopic (three-dimensional) images for motion pictures or television. In general, these techniques involve two camera systems in which two different pictures are taken from slightly different camera angles and locations. The object is to simulate the manner in which depth is perceived by a pair of human eyes, which are themselves slightly offset from each other and thus view images at slightly different angles. The two camera images are superimposed and presented to the viewer simultaneously on a television or movie screen. The images are then separated in some fashion for the viewer so that one eye sees only one image, and the other eye sees only the other image. In this way an illusion of depth is created by simulating normal vision.
One technique which has been used to implement this approach is called the anaglyphic 3-D process, and has been employed in motion pictures and television. This technique uses color filters to separate the two images. The images are color coded, for example with red and green respectively, and the viewer is provided with glasses having different colored filters in front of each eye. Each filter rejects the image that is not intended for that eye, and transmits the image which is intended to be seen by that eye. A red color filter will pass only the red image, while a green color filter will pass only the green image. If the left eye image is presented as a green image and the right as a red image, and a green filter is placed in front of the left eye and a red filter in front of the right eye, the proper images will be directed to the proper eye and a 3-D image will be perceived by the viewer. An example of the anaglyphic process is disclosed in U.S. Pat. No. 3,697,679, entitled "Stereoscopic Television System", by the present inventor Terry D. Beard together with Eric R. Garen. A major shortcoming of the anaglyphic method is that the color filters interfere with the presentation of a high quality full color image. Color filters which fully reject the undesired image are difficult to make, with the result that the 3-D effect is impaired. This process is also difficult to use successfully in television because of the limited bandwidth transmission of color information in commercial broadcasts. The result of this limited bandwidth transmission is either ghost image interference or low resolution images.
Another 3-D process used in motion pictures is the so-called "Polaroid" process, in which the left and right eye images are separated by the use of polarizing light filters. The left eye image is projected onto the screen through a polarizing filter rotated 45.degree. to the left of vertical, while the right eye image is projected onto the screen through a polarizing filter rotated 45.degree. to the right of vertical. In this way the polarization of the two images are at right angles, and similarly polarized filters placed in front of each of the viewer's eyes will cause the proper image to be transmitted to each eye. This method is not adapted for 3-D television, and its use for motion pictures requires a special non-depolarizing projection screen.
Another technique which has been used to produce 3-D images on television involves the sequential presentation of left and right eye images to the viewer, together with the use of synchronized electro-optical glasses to switch on the filter in front of each eye when its image is being presented. This process is complicated and expensive, and requires special broadcasting and receiving equipment and electro-optical glasses.